What is the purpose of specifying nodes in creating network topology?

[Anonymous]

I am clueless about the purpose of selecting nodes when creating a network topology. I have experimented with creating a dummy sewer network topology using Manhole blocks as nodes. The manhole blocks have an Attribute for an ID number. The resulting network topology includes the manholes as nodes, but the topology does not utilize the Manhole ID number from the blocks as topology ID numbers. Moreover, if I move a manhole, the links to it are not updated when I update the topology. I don't see any functionality at all for the manhole nodes either for analysis or for maintaining the integrity of the network. Really, what is the purpose of this option?

[Anonymous]

Hello Neil W.

I'll try to describe a simple example where specifying nodes might be useful....

Lets say you have a network topology representing water main lines... You could use nodes (blocks) to represent say the valves. Then on the 'analysis' side of things you could apply a large resistance value to that node (valve), which essentially 'turns the valve off'.

Hope this helps
Warren M

[Anonymous]

I understand how nodes are useful in analysis, but nodes are created automatically whenever a network topology is created. Thus there is no need to specify the water valves blocks as nodes since they do not provide any functionality above and beyond the default nodes. Am I correct on this? "Warren M" wrote in message news:4240448.1098476353772.JavaMail.jive@jiveforum1.autodesk.com... > Hello Neil W. > > I'll try to describe a simple example where specifying nodes might be > useful.... > > Lets say you have a network topology representing water main lines... You > could use nodes (blocks) to represent say the valves. Then on the > 'analysis' side of things you could apply a large resistance value to that > node (valve), which essentially 'turns it off'. > > Hope this helps > Warren M

[Anonymous]

Hi Neil.

Not sure I'm following, but...
Node 'objects' (actual points in the dwg) are only created if you specify to create them, or use existing objects as nodes.

Maybe you're referring to the command line response after creating a topology:

I created the following topology without specifying any existing objects, or new objects, for the nodes, but it still reports 14 nodes created...

Creating Network topology: Test....
Writing topology information to the drawing...
Topology successfully created with 15 links and 14 nodes.

This number is just reporting the number of nodes, but there are none 'drawn' in the dwg...

Hope this helps
Warren M

[Anonymous]

What I am trying to understand is how to use the nodes that are created from the selected blocks in analysis and maintenance, since the blocks are not utilized in the topology object data. For example, if I have 2 manhole nodes connected by a link representing the sewer main, and those manholes have an identifier attribute (say Manhole ID#100 and Manhole ID #2000), when I create the network topology, the nodes assigned to the ends of the sewer main link are not nodes #100 and #200, but have nodes that are created by Map. The sewer manholes play no role in the resulting topology that I can see. Thus if I were to move one of the manhole blocks, I would expect the sewer link should adjust to maintain connection to them, since I specified them as nodes. This is not the case as you can see by experimenting with your test topology. Moving the manhole will cause Map to report an error in the topology to the effect that the node is out of position, but it does nothing to correct the links. In fact if you audit the topology, Map reports it is incorrect. If you then tell map to recreate the topology, it will create a new node at the end of the link where the manhole used to be and the manhole will be completely disconnected from the topology. As you have noted, map creates nodes at the ends of the links, even though these nodes are not entities in the drawing. However, those nodes do play a role in the analysis by means of the object data assigned to them when the topology is created. These are the nodes that provide the data that Map utilizes in analysis. The attributes of the blocks that we select seem to be useless for analysis or maintenance. So what I am failing to understand is: what do we gain from specifying blocks as nodes when we create the topology? "Warren M" wrote in message news:20965782.1098718729501.JavaMail.jive@jiveforum1.autodesk.com... > Hi Neil. > > Not sure I'm following, but... > Node 'objects' (actual points in the dwg) are only created if you specify > to create them, or use existing objects as nodes. > > Maybe you're referring to the command line response after creating a > topology: > > I created the following topology without specifying any existing objects, > or new objects, for the nodes, but it still reports 14 nodes created... > > Creating Network topology: Test.... > Writing topology information to the drawing... > Topology successfully created with 15 links and 14 nodes. > > This number is just reporting the number of nodes, but there are none > 'drawn' in the dwg... > > Hope this helps > Warren M

[Anonymous]

I think I grasp the significance of the blocks now after doing some more analysis. While map does create it's own default nodes when creating the topology, there is no way to edit the resistance values of those nodes unless they are entities in the drawing that can be selected. We can tell map to create entities for the nodes or we can select our own objects. When we select the objects (blocks) to be used as nodes, then Map can draw on values from the attributes and object data that are assigned to those blocks to use as resistance values during analysis. At least this is what appears to be the case from my experiments. "no spam" wrote in message news:417d2c13_2@newsprd01... > What I am trying to understand is how to use the nodes that are created > from the selected blocks in analysis and maintenance, since the blocks are > not utilized in the topology object data. For example, if I have 2 manhole > nodes connected by a link representing the sewer main, and those manholes > have an identifier attribute (say Manhole ID#100 and Manhole ID #2000), > when I create the network topology, the nodes assigned to the ends of the > sewer main link are not nodes #100 and #200, but have nodes that are > created by Map. The sewer manholes play no role in the resulting topology > that I can see. Thus if I were to move one of the manhole blocks, I would > expect the sewer link should adjust to maintain connection to them, since > I specified them as nodes. This is not the case as you can see by > experimenting with your test topology. Moving the manhole will cause Map > to report an error in the topology to the effect that the node is out of > position, but it does nothing to correct the links. In fact if you audit > the topology, Map reports it is incorrect. If you then tell map to > recreate the topology, it will create a new node at the end of the link > where the manhole used to be and the manhole will be completely > disconnected from the topology. > > As you have noted, map creates nodes at the ends of the links, even though > these nodes are not entities in the drawing. However, those nodes do play > a role in the analysis by means of the object data assigned to them when > the topology is created. These are the nodes that provide the data that > Map utilizes in analysis. The attributes of the blocks that we select seem > to be useless for analysis or maintenance. > > So what I am failing to understand is: what do we gain from specifying > blocks as nodes when we create the topology? > > > "Warren M" wrote in message > news:20965782.1098718729501.JavaMail.jive@jiveforum1.autodesk.com... >> Hi Neil. >> >> Not sure I'm following, but... >> Node 'objects' (actual points in the dwg) are only created if you specify >> to create them, or use existing objects as nodes. >> >> Maybe you're referring to the command line response after creating a >> topology: >> >> I created the following topology without specifying any existing objects, >> or new objects, for the nodes, but it still reports 14 nodes created... >> >> Creating Network topology: Test.... >> Writing topology information to the drawing... >> Topology successfully created with 15 links and 14 nodes. >> >> This number is just reporting the number of nodes, but there are none >> 'drawn' in the dwg... >> >> Hope this helps >> Warren M > >